Method of making aluminum-alloy articles.



UNITED STATES PATENT OFFICE.

ALFRED WILM, OF gIIAGHTENSEIli-BERLIN, GERMANY.

HE lHUD O1" MAKING ALUMINUMAI|LOY ARTICLES.

Patented Apr. 9, 1918.

No Drawing. Application filed Bay 24, 1812, Serial 110. 698,658. RenewedAugust 23, 1917. Serial No. 187,887.

To all whom it may concern:

Be it known that I, ALFnuo WILM, a subject of the King of Prussia,Emperor of Germany, residing in Schlachtensee-Berhn, Germany, haveinvented certain new and useful Improvements in Methods of MakingAluminum-Alloy Articles; and I do hereby declare the followir to be afull, clear, and exact description ot the invention, such as will enableothers skilled in the art to which it appertains to make and use thesame.

The present invention relates to aluminum-alloy articles, and to amethod of making the same which is directed to obtaining a. uniformclose-grained texture of the metal of the articles, of such a characteras to imart thereto increased strength, rigidity, and mertness toelectrolysis. The departure from the known procedure which characterizesthis invention lies in bringing about a close-grained texture of themetal of al-uminum-alloy articles with a uniform distribution of themetallic constituents through the mass, by selecting such metals and insuch proportional quantities as will admit of the formation of anarticle from a molten admixture thereof, which will subsequently becomeintimately and uniformly associated throughout the mass of the articleunder the influence'of a degree of heat less than would be required todestroy the form of the article, and which will ultimatelv be fixed insuch intimate and uniform association in the mass bythe withdrawal ofheat at a rate which will not allow time for their loss intimate or lessuniform redistribution therein.

The correlation of the admixture of chosen meta-ls with the particulartreatment to which it is subjected can be varied to some extent toeffect differing degrees of hardness, ductility and strength in themetal of the article produced, butthe limits of permissible variation inthe quantities of the metals used to efl'ect advantageous results arewell defined, as will appear from the foL lowing description.

In order to produce an aluminum-alloy article havin the desirablecharacteristics enumerated 9. ve, it has been necessary to discover whatmetals and what proportions of said. metals, when admixed with amajorquantity of. aluminum, would as ume an in:- tmlate association and.uniform distribution in. a mass at some temperature below the congealingpoint of the mass. Thus I have found that when approximately one-half ofone per cent. of magnesium is added to a molten admixture of aluminumwith approximately from 3 to 6 per cent. of copper and a quantity ofmanganese approximating one-seventh of the copper content, an articleformed from said admixture can be given the required texture, resultingin a marked increase in strength and rigidity and resistivity toelectrolytic decomposition, by cooling it from a temperature ofsubstantially 500 C. with sufiicient rapidity to in When the aluminum ismeltedand the crucible charge is at a red heat it is stirred for a shorttime with an iron rod, whereupon the temperature of the charge will riseto white heat owing to the heat generated by the reduction of themetallic oxids of oopper and manganese in the aluminum. The aluminumoxid thus ormed rises readily to the surface of the charge and may beremoved as a scum by a rod. Another quantity of foul-kilograms ofaluminumis now added, stirred u and the molten admixture thereuponquickly poured out into a shallow iron mold to chill. This rich alloycontains a relatively large quantity of manganese which would settle outif the charge were allowed to cool slowly. Q

The rich alloy is melted with an added amount of aluminum to bring thecopper content to from 3 to 6 per cent. of the mass, as the requirementsof the product may call for. Approximately one-half of one per cent. ofmetallic magnesium is now added to the molten mass, preferably after it.has been removed from the smeltin furnace, and the charge is formed intot e article, congcaling in the form required for the article which maybe an ingot, a bar, or a cast shape of any other kind.

As it is usually diflicultto coola cast piece in the mold. to apredetermined temperature throughout, I prefer to reheat the piecethroughout, when it is desired to effect the uniform distribution of themetals, to a temperature lyin between 420 C. and 560 C. and preferab?closely approximating 500 C. and therea ter cool itto the normaltemperature with sufficient rapidity to revent substantial separation ofthe metal ic constituents from the uniformly distributed condition towhich they have been brought by the heat treatment, as, for example, byquenching it in water. i

The presence of copper in the alloy in excess of six per cent. willgenerally revent the obtaining of a fine-grained uni ormlydistributedtexture, by the application of any temperature below the congealingpoint, while the addition of magnesium in quantities above two per cent.or much below .5 per cent. will prevent the attainment of the requisitehardness.

While I prefer to add magnesium in the proportion of approximately onetwo-hundredth part of the aluminum content of each particular alloy, thediflerence is so trifling that for commercial practice I add .5 percent. of the entire mass for any alloy within the limits herein given.

Heretofore, articles made of aluminumalloys containing a large ercentageof aluminum have not possessed uniform distribution of theconstituentmetals through the mass, and have consequently suffered fromelectrolytic decomposition when exposed to air and moisture and were oflittle or no value as fittings exposed to salt water.

as in marine construction.

The treated alloys herein described resist the action of salt water to aremarkable degree.

Among other metals which may be used in the aluminum alloys hereindescribed and permit uniformity of distribution with the aluminum, are.silver, vanadium, nickel, chromium, tungsten, molybdenum and titanium,vany of which will produce advantag eo us characteristics as to strengthand rigidity in the treated allo -article.

Alloys having certain peculiar advantages forcommereial purposes may,for example, be compounded as follows With alleys of very great hardnesswhich are obtaine by the use of an increased proportion pf copper andmagnesium, that is to say, with copper up to 5% and magnesium up to 2%,an addition of nickel in suitable proportions will serve to reduce thebrittleness of the product without interfering with the uniformdistribution of the con stituents. Thus an alloy of about 93.25aluminum, 6% co per, 5% magnesium and 25% nickel has t e characteristicqualities above referred to, with increased ductility. Ora-particularlygood alloy is formed by alloying wmd "treating as above described 94.5parts aluminum, 4 parts copper, nesium and 1 part nickel.

By employing chromium in about the proportions 94.5 parts aluminum, 4parts copper, .5 parts magnesium and 1 part chromium, the capacity totake and retain a polish is increased.

For friction surfaces it is of advantage to use titanium in about theproportions 94.5 parts aluminum, 4 parts copper, .5 parts magnesium and1 part titanium.

In using an alloy containing iron, I have found the followingcomposition particularly suitable for practising my invention, viz.:aluminum 94.25 parts, copper 4 parts, magnesium .25 and iron 1.5 parts.V

In fact a material of great value for certain well-defined purposes'maybe produced by adding magnesium alone to the aluminum in about theproportion of 200 parts of aluminum to 1 part of magnesium and thensubjecting the material to the heat treatment above described. Theresult is to in- .5 magcrease the tensile strength and particularly tomake the material easier to work or shape. For purposes such as themanufacture of cooking utensils and the like, where ease of working ismore important than tensile strength the magnesium is added in lessamount, as for example, about 2% to .3%.

It is to be understood that where the material is to undergo machiningoperations, such as rolling, drawing, turning, swaging and .the like,the heat treatment should follow such operations, though slight changesin shape, such as flanging or bending, are

permissible immediately after the heat treatment.

Having thus described my invention, what I claim is:

1. The method of manufacturing artlcles of aluminum alloys whichcomprises forming the article from an admixtureof aluminum and one ormore other metals m quantities which will assume an adequately umformproportional distribution throughout the mass within a range of temerature lying' below the fusing point 0 the alloy, maintaining theformed article at a temperature within said range until said uniformproportional distribution of the metals is attained, and cooling thearticle at a rate which will insure fixation of the uniformly low-thecongealing point of-themutinno taining the formed article at atemperature within said ranlge until said uniform proportional distriution of the constituents of the admixture is attained, and cooling thearticle at a rate. which will insure fixation of the uniformlydistributed alloy; substantially as described.

3. The method of manufacturing articles of aluminum alloys whichcomprises the making of a molten admixture of suitable proportions ofaluminum and one or more other metals, adding to said molten admixture aquantity of ma esium approximately equal to one-two-hun redth part ofthe aluminum content of said admixture, subjecting an article formedjromsaid admixture to a temperature somewhat below the congealing point ofsaid admixture until an adequately uniform proportional distribution ofthe metals is attained throughout the mass and cooling the article tothe normal temperature at a rate which will insure fixation of theuniformly distributed proportions; substantially as described.

4. The'method of manufacturing articles 'of aluminum alloys whichcomprises the making of a molten admixture of suitable proportions ofaluminum, copper and manganese, the quantity of manganese beingapproximately equal to one-seventh of the copper content of theadmixture, adding to said admixture a quantity of magnesiumapproximately equal to one-two-hundredth part of the aluminum content ofthe admixture, subjecting an article formed from said admixture to atemperature somewhat below the congealing point of said admixture untilan adequately uniform proportional distribution of the metals isattained throughout the mass and cooling the article to the normaltemperature at a rate which will insure fixation of the uniformlydistributed proportions; substantially as. described.

5. The method of manufacturing articles of aluminum alloys whichcomprises the making of a molten admixture of aluminum, copper andmanganese, the copper content of which is limited to from 3 to 6 percent. and the manganese content being proportional to the amount ofcopper in the ratio of one art manganese to seven parts copper adding tosaid admixture ap roximately .5 per cent. of magnesium, su jecting anarticle formed from said admixture to a temperature lying above 420 C.until an adequate uniform proportional distribution of the metals isattained throughout the mass and cooling the article at a rate whichwill insure fixation of the uniformly distributed proportions;substantially as described.

In testimony whereof I aflix my slgnature, in presence of two witnesses.

ALFRED WILM.

Witnesses HENRY Hasrnn,

Wownmm Ham.

It is hereby certified that in Letters Patent No. 1,261,987. grantedApril 9, 1918, upon the application (if Alfred Wilm, ofSchluclitvnscv-Beriin, Gvrrmmy, for an improvement in Mcthmis of MakingAlumimim-Alioy Artic lns," an errur appears in the printed specificationrequiring correction as foilowei: Page 2, line (51, for the nunn'ml andcharacter 5% read 5%; and that the said Letters Patent shonld be mm!with this correction therein that the same may conform to the record ofthe case in the Patent Ollice.

Sig 'ned and sealed this 30th day of April, A. D., 1918.

[SEAL] F. W. H. CLAY,

Acting C'omm'iss'ioner of Patents. C1. 75--1

